A high-frequency circuit of a wireless terminal such as a mobile phone includes a duplexer including a transmission filter and a reception filter coupled to a common antenna terminal. Used for each filter is an acoustic wave filter using an acoustic wave such as a surface acoustic wave (SAW), a bulk acoustic wave (BAW), a LOVE wave, a boundary wave, or a Lamb wave (e.g. Japanese Patent Application Publication No. 2008-263624).
Multi-functionalized and sophisticated wireless terminals require a filter and a duplexer having good characteristics (low-loss, wide bandwidth).